Thread milling machine



Augym, 1945.

FBG.

A. J. FRANCE THREAD MILLING MACHINE Filed Feb. 2, 1942.

e sheets-sheet 1 ATTORNEY.

Aug 14, 1945. A. J. FRANCE 2,382,662

THREAD` MILLING MACHINE Filed Feb. v2, -1942 e sheets-sheet 2 1 wromATTORI'YAEY.

6 Sheets-Sheet 3 A. J. FRANCE THREAD MILLING MACHINE Filed Feb. 2, 1942I INVENTOR.

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THREAD MILLING MACHINE Filed Feb. 2, :L9/l2 6 Sheets-Sheet 4- vVQINVENTOR.

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Aug. M, 1945-. A. J. FRANCE d 2,382,662

THREAD MILLING MACHINE Filed Feb. 2, 1942 6 Sheets-Sheet 5 TTORNE Y ug.14, 1945. AQJ, PRANC THREAD MILLING MACHINE 6 Sheets-Sheet 6 R. m m WFiled Feb. 2, 1942 ATTORNY.

Patented Aug. 14, 1945 THREAD MILLING 'MACHINE `Albert J. Prance,Detroit, Mich., assignor to Murchey Machine & vTool Company, Detroit,Mich.,;a corporation of Michigan "v Application February 2, 1942, SerialNo. 429,240

3 Claims. 4(C1. :a0-11.56)

The present invention relates to thread milling machines.

Among the objects of the present invention is a thread milling machinewhich is fully automatic in its operation, is economical to constructand does not easily get out of order.

Another object is a machine which Will produce a more accurate and moreflnely finished thread than is the case with .known thread millers.

Another object is a thread miller which, when adjusted for a particularoperation will duplicate the work substantially indefinitely withoufurther adjustment.

Still other objects and advantages will be apparent to those skilled inthe` art upon refer- Vence to the following descriptionand theaccompanying drawings .in which Figure 1 is anend elevation, partlysectionaLx` as from the right of Figure 3.

.Figure 2 is an end elevation, partly sectional, as from the left ofFigure `3. i

Figure 3 is a centralvertical sectional View, with parts in elevation.

Figures 4 and 5 are sectional views. of certain details of construction.

Figure 6 is a partial rear view ofthe maz chine.

Figure 7 is a sectional view showing a detail of construction.

Figure 8 is -a planview of the fluid circulation elements, theconnecting conduits being omitted for the sake of clarity.

Figure 9 is an electric wiring diagramand Figure 10 is a uid circulationdiagram.

In the drawings, a suitable base III serves as a housing of variouselements -and also as a-support, at one end, of the cutting spindle andassociated elements and, at the other end, of the Work ysupporting'slideand its associated parts.v

The latter may be and preferably is a'simple sliding table II movablelongitudinallyof` the base toward and from the cutter by Vmeansfof asuitable hand Wheel I2 and its vpinion I3-and rack I4.

It is to be understood that suitable work'supporting jigs (not shown)will be used in mounting the work piece thereon; an end of such a fpiece being shown in Figure 3 at I5.

The sole function of table II is work-support and movement into andfroma suitablelocation for threading. Y

Mounted upon the base III vand in alignment with the `table II is aframe member 2l! `provided with bearings zi in which is mounted forrotation a cylindrical sleeve 22rv bored eccentrically and carrying asecondcylin'drical sleeve 23 also bored eccentrically. Within thheeccentric bore of sleeve `23 and carriedin suitable antifrictionbearings 24 is a toolcarryingspindle 25, an inside threading millingcutterbeing shown at26.

yThe spindle 25 isdriven by means of asuitable sprocket 30 andlink belt3| from a gear or sprocket v32 (see,Fig.,4) keyed to a short shaft 33which is driven,'through gears 34 and 35 and shaft 36, from the pulley.31, the ylatter being vin turn driven through'belt 38vby the elec- Atric motor 39. I

In order to provide for the lateral or translative movement of thespindle 25 (to be described) without interference with` lthe, drivethereof, the driving connection from motor 39 to the spindle is arrangedto permit such movement, and such arrangement is shown in Figures 2 and4.

In these figures, the bearing supporting mem'- bers 36a are stationaryparts of the supporting base III andhave xed in suitable openings asleeve 36h serving to support the vshaft 36 in suitable antifrictionbearings` 36e. This sleeve 36h also serves as a shaft orspindleuponwhich are rotatably mounted the arms 33a vof the bearing support33h, having mounted therein the shaft 33, suitable antifriction bearings33e being provided. Thev assembly. of gears 32 and -34 vwith shaft `33is, therefore,.movable around .30 and 32 as the spindle moves.

A-variation in the drive speed for the spindle 25 is provided for bymounting the motor` 39 upon va vertically swingable platform 39a towhich is attached la .link y39h in turn connected to a threaded shaft39e coacting'with the bandwheel 39d. 'I'he pulley 38a is soconstructedthat its fiangesmove'toward each otheras the motor 39 and itsplatform are lifted. y

As indicated above, the spindle 25,"i n addition to its rotative`movement'is also movable laterally in order to feed the cutter towardand'from the work. This lateral vor translative movement is producedbythe relativerotatlon of the *two 22E serve as stops for an arm 23Amounted upon sleeve 23 and projecting from slot22A between rails 22B andadapted to coact with the stop Y Loosely mounted upon sleeve 22 is aworm gearl 50 located adjacent the rails 22B and provided with laterallyextending ngers SUAspaced sufciently toembrace closely the arm 23Awhereby to move the latter between the stop screws 22E,` when said gearisactuated, and thereby move the sleeve 22 as a unit with sleeve 23.Further, in order to provide against movement of sleeve 23 until the arm23A reaches one of the stopscrews 22E, stationary brake means for sleeve231s prol vided.

This brake means is shown in Figures 2 and 3 as a brake shoe anchored tothe housing 20 as by the screw 52.

The worm gear 50 is driven by a suitable wormv on shaft 53 in turndriven throughthe small gear54 meshing with a large gear 55 fixed toshaft 56 mounted in the housing or frame' 2U of the machine. The outerend of shaft 56 has xed thereon a small pinion 5'! which is adapted tocoact with a rack 60, longitudinal movement of which produces therelative movement of the sleeves 22 and 23 and also rotation of thesesleeves as a unit. v

Figure 6, showing a rear view of the machine,

- shows the rack 6U and the pressure fluid cylinder 6| within which is apiston (not shown)v connected by rod 62 to the rack and actuated bysupplying lluid under pressure to either end of the cylinder through thepipes 63.

In the operation of the machine, as thus far4 described, when an insidethread is to be milled, the work piece. l5 is moved into position overthe cutter 26 which is centered with respect to the work because of therelative position of sleeves 22 and 23.

-. When the machine is then put intol operation by setting up therotation of spindle and starting the operation of rack 60, the worm gear50 starts to rotate and, through ngers 50A, parl tially rotates sleeve23 within sleeve 22,' the amount of rotation depending upon the travelof arm 23A between the stop screws 22E, for example, from the position23AA in dotted lines to the full line position of 23A. 'In this partialrelative rotation, the sleeve 22 is held by the brakel until the arm 23Astrikes the stop screw and therefore provides for the lateral movementof the spindle 25.

This lateral'movement is adjusted by the screws.

22E and is the feed of the cutter into the work and therefore the depthof the cut.

When the arm 23A strikes the stop screw 22E, the gear 50 continues toturn the sleeve assembly for slightly more than a complete revoluqthrough the means shown in Figures 8, 9 and 10, in which (in Fig. 8)there is shown a motor 90 directly coupled to a suitable pump 9|, whichis arranged to draw suitable fluid from a tank 92 5 serving as a baseupon which the motor, pump and other elements may be mounted. The pump9| draws its fluid from tank 92 through the pipe 93 provided,preferably, with a screen 94.

' .l "From the' pump 9|the f luid'is, conducted to a magneticallya'ctuatedvalve V to the port C and from the valve V is conducted'through pipes D 'and E to one end or the other of the cylinder 6|,depending upon whether the valve is in position to connect port C withport A, from which leads pipe D, or port B, from which leads pipe E. The

- fourth port Tis 'connected to a pipe T| leading backto the'tank 92.

. In the valve V, the mechanism is so arranged that the ports A and Bare alternately connected to port C and port T. When it is desired toactu- .ate the rack 60 ina thread lcutting operation,.the

valve V'is'set to' connect the pump discharge into ,port C withthe portA, whereupon uid is forced directly'to' the end BI of cylinder 5|.Atythe same time, port B is connected to port T for the dis, charge offluid fromthe end AI of thecylinder Kback to thetank 92.

` This discharge, however, is regulated and 1 throttled,whereby'to'control the speed of movement of the rack.v This throttlingand'control lis l provided forby theseveral valves F, G, H and Iofwhich', the valveuF is a check valve allowing fluid to ilow from thepumpto the cylinder, but preventing back flow.

. I'he valve Gr is a cam operatedl valve actuable yby a cam BDA carriedby the rackll. This valve Gis closed or nearly so when the rack is instarting position. If itis desired to provide the rack =with an initialslightly higherspeed, the cam 60A may slope slightly Iupward toward theleft end l(Fig. 10), At or near. its other en d it slopes l'sharplyupward so as toallow quick and full opening of the valve.

The valves I-I and I arehand-controlled and dial set, and lcalibratedtoindicate ,the speed of rack movement. Of these, the valve H isarranged to pass less fluid than the valve I.`

When the nuid'fiowis beginning into end Bl I of the cylinder, thedischarge from end AI is through pipe A2 to the valve H, since' bothvalves F and G are closed toits passage. From valve H the flowis'through pipe HI, and pipe vE back to port B of valve vV which' isconnectcdtoport T and through pipeTl totank 92. As soon, .how-

' ever, as'the rack 60 has, moved'far enough to allow the camI 6| 1A`toopen or permit the opening of valve G, the flow is through both ValvesHand I, but chiefly through valve I, since the valve G is open. The flowis, ofl course, through valve H, pipe G2, valve G, pipe GI te port B, toport T and thenceftotheftank 92. Consequently, Ythe rack may move at ahigheryspe'ed.

When it is desired to return the rack 60 to the vstarting point, the`valve V set so that the port C is connected to the port B and port Aconnected to port T. In this position of the valve V, fluid y passesfrom'the pump through pipe E, check valve F,'and directly tothe end AIof cylinder 6|, while the fluid from 4end-BI of the cylinder flowsunrestricted through pipe D, valve V, and pipe `T| to tank 92. .Y f

`vIn addition to the several elements of valve V which have already beenmentioned.- means isalso provided for permitting the pump 9| ltodischarge (5 directlyrback to the tank during the, periodrwhen the rack6| is at rest. Such means is indicated in Figure 10 by the conduit 9 IA.

In Figure 8, there is also shown a second pump |00, belt-driven by motor90 and adapted to draw cutting uid from tank IUI (see Fig. 3) andthrough a suitable nozzle (not shown) flow it over the work and cutter.The pipe 'H32 is shown (see Fig. 3) as the point cf attachment of thenozzle.

In Fig. 9, the power supply lines P lead to the transformer Pl, andthence to a multiple solenoidA switch S to which are connected thesolenoids operating the valve V, a pair of rack operated switches, astarting switch and a quick return switch.

In the diagram shown in Figure 9, the valve V is shown diagrammaticallybeing represented as a pair of simple valves actuated by solenoids.

When it is desired to start operation of the rack 60, the rack switch Kis held open by a suitable cam on the rack, the button L is pressed andcompletes a circuit through L2, Lly Sl, solenoid S2, and L3. Thiscircuit closes contacts M and Ml and completes the circuit L2, MI, M2,solenoid M3, L3, thereby operating valve V to start the rack andallowing switch K to close.

At the end of the rack travel, a suitable plate or cam thereon strikesand closes rack switch N, and thereby establishes the circuit throughsolenoid S3, this circuit being L2, NI, N, N2, S3 and L3 and closingcontacts R and RI and opening contacts R2, the latter breaking theholding circuit for solenoid S2.

Contacts Rl complete a holding circuit for solenoid S3, which circuit isL3, Rl, Kl, switch K, N l, L2.

Contacts R complete a circuit L2, R, WI, valve solenoid W, W2, W3, L3,thereby reversing the valve V and consequently the motion of rack 60.

Upon reaching the end of the return stroke, the switch K is openedtobreak the holding circuit and allow solenoid S3 to become deenergizedand thereby reestablish the idle position.

If for some reason, it is desired to return the rack after a partstroke, the button X is pressed. The effect of this is to therebyestablish a circuit L2, X, XI, S3, L3. This, of course, has the sameeffect as described above for the switch N.

It is to be understood that the invention may be embodied in otherspecific forms without departing from the spirit or essential attributesthereof, and it is desired that the present embodiment be considered inall respects as illustrative and not restrictive; reference being had tothe appended claims rather than to the foregoing description to indicatethe scope of the invention. I claim:

1. In a thread milling machine, having a pair vof eccentric sleeves, onewithin the other, and a cutter carrying spindle rotatably mounted withinsaid sleeves, means for relatively rotating said sleeves and thenrotating said sleeves as a unit, said rotating means including areversible hydraulic motor having cam actuated meansfor changing thespeed thereof at a predetermined time during the forward or feedingportion of the cycle of operations.

2. In a thread milling machine, having a pair of eccentric sleeves, onewithin the other, and a cutter carrying spindle rotatably mounted withinsaid sleeves, means for relatively rotating said sleeves and thenrotating said sleeves as a unit, said rotating means including areversible hydraulic motor having means for reversing the flow of uid toand from said motor whereby to reverse said motor, cam actuated meansfor throttling the outflow of iiuid whereby to regulate the speed ofsaid motor and means for changing the degree of throttling during theforward or feeding portion of the cycle whereby to change the cuttingfeed.

3. In a thread milling machine, having a pair of eccentric sleeves, onewithin the other, and a cutter carrying spindle rotatably mounted Withinsaid sleeves, means for relatively rotating said sleeves and thenrotating said sleeves as a unit, said rotating means including areversible hydraulic motor having cam actuated means for changing thespeed thereof at a predetermined time, said speed changing meansconsisting of a plurality of valves capable of passing different amountsof fluid and connected to the outilow of said motor, and means forblocking the flow through one of said valves during part of theoperation of said motor and then opening said valve during the remainingpart.

' ALBERT J. PRANCE.

